An expert who has achieved level 2 by getting 100 points
An expert that got 5 achievements.
An expert whose answer got voted for 100 times.
An expert who has written 50 answers of more than 400 characters.
Re: Auto focus will not work with the 100-400mm 5.6
It's the same 3 as with the 1.4x, but be warned it is likely to be a very unsatisfactory solution in all but the very brightest daylight, and the lens will continually hunt for autofocus - you risk burning out your focussing motor.
If you really want to experiment, hold the converter so the writing on it is the correct way up. Looking at the row of gold pins, rotate the lens so they are at the top, or the 12 o'clock position. It is the 3 leftmost pins you want to cover. Use a piece of sellotape (scotch tape) to cover the three pins, you'll have to cut a thin strip to do it. Be careful as the tape could slip as you attach the converter to the lens adding more risk to the experiment if it gets stuck somewhere it shouldn't!
I tried this with my 2x (version 1) and a 70-200f4/L, it tries to focus but fails with the much reduced light. Might try it outside on a sunny day, but also scared of damaging my lens!
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
First of all you need to clean the connectors on both the lens and the camera. Do this by using a pencil eraser being careful not to get bits in the camera or lens. If this doesn't clear the problem is it that auto focus doesn't function with any lens. If that is so then you need a camera repair. If auto focus is only non functional on the Sigma 170-500mm and you can manual focus then the probable problem may be a broken ribbon cable in the lens itself. This will need to be replaced. Usually a quick and relatively cheap job.
You may just have the left auto focus points selected. You don't say which camera model you have. If on the back of your camera you can see a button with an icon showing 5 small white blocks in a plus sign in a white box press this to select the auto focus points. It should show the available auto focus points and then use the left/right (wheel) button to change the selection
there is couple of possibilities like wise when you zoom lens manualy and can you heard the hard noise then could be AF unit itself faulty. AF unit gear is gone.
could be AF shaft broken thats why not focusing
could be AF Flex broken thats why not focusing
for that please bring to canon service center
You haven't stated which body you have but the AF will not work with the extender if the effective lens aperture is too low (remember that a 2x extender doubles the focal length but halves the effective aperture).
Canon's own website states: "Autofocusing does not operate if the effective maximum aperture is
greater than f/5.6 (greater than f/8 on the EOS 1V and EOS 3)."
The EOS 40D only use auto focus up to aperture 5.6. Only the 1-series use auto focus up to aperture 8.
The adapter adds 1 stop to the lens aperture. Since the 100-400 is a 4.5-5.6, the aperture range with the extender mounted will be 6.3-8.
There is a work around though. Just place a thin strip of insulating tape over the three pins on the lefthand side (lens side of the extender). No damage will occur to the camera or teleconverter.
This is because the camera will not expose a picture until the auto focus is locked. If you are shooting in dimly lit conditions, the AF might have a hard time obtaining a lock. Using the flash as auto focus assistance many time helps in this condition.
Another reason might be that you try to focus on even surfaces with low contrast. The auto focus work by sensing contrast. Even surfaces, such as a white wall or the sky, have very little contrast, therefore the auto focus will not be able to obtain a lock.
The solution here is to point the AF sensor at something with more contrast, such as an eye, a pole, or basicly anything that have edges/lines.
I hope this help you!
Did it ever work on this camera?
I have seen some Sigma lenses that are auto focus on canon film cameras but then when put on the digital they dont work right. If you have used it on this camera then make sure the lens is clean.sometimes dirt on the front wil make it try focusing on the dirt. Next try focusing in manual focus to make sure the focus is working. Then take the lens off and then put it back on and make sure it clicks into place.
Let me know if none of those things work. also make sure to try focus on something close and somthing far away.